In data for an undetermined length of

In this lesson, we will discuss the session layer, layer 5 of the OSI model.

We will talk about how the session layer sets up, manages, and maintains multiple network communicative sessions, and you’ll learn about APIs like NetBIOS and TCP/IP.

Our Authors Write a Custom Essay
For Only $13.90/page!


order now

What Is the Session Layer?

Say you are planning and hosting a large party. Initially, the problems are minor;like small issues with the food or party favors;but as the party activity increases, time and management become critical. To manage the event and keep your party on track, you need additional helpers to interface with the caterer, florist, and baker. With the setup problems solved, the helpers continue providing assistance by giving management support ensuring each activity runs smoothly.

At the party’s conclusion, the helpers aid in cleaning up, closing party facilities, and terminating connections.You may be wondering what a party has to do with networking, particularly the session layer? We can make a comparison between setting up, managing, and closing the party with the functions performed by the session layer, which is layer five of the seven layers comprising the Open Systems Interconnection (OSI) model.

What Is the Open Systems Interconnect Model?

Before we can begin our session layer discussion in greater detail, we need to look into the networking environment in which the session layer exists: the OSI model. The OSI model has seven protocol layers, with each layer performing a specific and supportive communicative task.

For a brief recap, let’s go over each of the layers from top to bottom:

  • Layer 7: the application layer – provides access to available network resources
  • Layer 6: the presentation layer – translates, encrypts, and compresses data
  • Layer 5: the session layer – establishes, manages, and terminates communicative sessions
  • Layer 4: the transport layer – provides reliable process-to-process message delivery and error recovery
  • Layer 3: the network layer, – moves packets from source to destination providing internetworking capabilities
  • Layer 2: the data link layer, – organizes bits into frames providing node-to-node delivery
  • Layer 1: the physical layer – transmits bits over a medium establishing mechanical and electrical specifications

Here, we see an illustration of data flow to and from the sending and receiving computers on a network. As seen here, the session layer provides communicative support to the OSI model’s presentation (6) and transport (4) layers.

Understanding the Session Layer

Networking is defined as a grouping of two or more computers being linked together to exchange data.

As layer 5 of the OSI model, the session layer is primarily responsible for setting up and managing communicative sessions, thereby enabling the sending and receiving of data for an undetermined length of time—similar to a telephone call. Additionally, the session layer is responsible for terminating sessions between software processes.As was the case with our party helpers, the primary responsibilities of session layer protocols (our helpers) are to set up, control, maintain, and close communicative sessions. Common session layer helpers are often referred to as application programming interfaces (APIs).

A common example of an API is the network basic input/output system (NETBIOS), which allows applications on separate computers to communicate over a local area network (LAN). Another example is the use of transfer control protocol/internet protocol (TCP/IP), which standardizes communications. APIs such as these are of primary interest to programmers and developers of application software for completing network communication setup and simplifying management.As part of the OSI model, the session layer determines what format will be used for data exchange between the engaging nodes on a network. As long as the established format is in place, the communications channel will maintain an open status. Looking back at your party, you had to set up a session (the party) by arranging and managing session formats with items such as the guest list, party favors, food, flowers, and baked goodies.

Since you had helpers (APIs), you were able to control the environment, had a great session (party), and closed related activities gracefully.

Session Layer Functions and Protocols

As a functional part of the OSI model, the session layer establishes, controls, and ends sessions occurring between communicative applications. Primarily, the goal for the session layer is to coordinate active applications on various hosts using assigned protocols.Six of the more popular session layer protocols used to handle service requests (program commands) and their associated replies include:

  • Network file system (NFS)
  • Structured query language (SQL)
  • Remote procedure call (RPC)
  • X window system
  • AppleTalk session protocol (ASP)
  • DEC session control protocol (SCP)

This graphic shown here illustrates two host computers using one or more of these protocols to process commands.

When programming session layer functionality using the protocols we have identified, programmers must pay strict attention to established session layer guidelines.

By doing so, they ensure the data format and structure is acceptable by the presentation layer (6) and the transport layer (4).

Lesson Summary

Let’s review what we learned. In networking, the open systems interconnection (OSI) model has seven layers that each do a specific and supportive communicative task.

From top to bottom (layers 7 to 1), they are the:

  • Application layer
  • Presentation layer
  • Session layer
  • Transport layer
  • Network layer
  • Data link layer
  • Physical layer

We focused on the session layer, the fifth layer, which is responsible to set up, manage, and maintain network communicative sessions. We also learned about common session layer helpers called APIs. APIs like NetBIOS and TCP/IP determine structure and format guidelines supporting presentation (6) and transport (4) layer programming by network engineers.

Finally, we talked about the popular session layer protocols used to handle service requests and their associated replies. These included:

  • Network file system (NFS)
  • Structured query language (SQL)
  • Remote procedure call (RPC)
  • X window system
  • AppleTalk session protocol (ASP)
  • DEC session control protocol (SCP)

Prominent Terms ; Their Explanations

sessionlayerterms
Terminology Explanations
Open Systems Interconnection (OSI) model with seven layers that each do a specific and supportive communicative task
Networking a grouping of two or more computers being linked together to exchange data
Application programming interfaces (APIs) common session layer helpers
Network basic input/output system (NETBIOS) allows applications on separate computers to communicate over a local area network (LAN)
Transfer control protocol/internet protocol (TCP/IP) standardizes communications
Popular session layer protocols Network file system, structured query language, remote procedure call, X window system, AppleTalk session protocol, and DEC session control protocol

Learning Outcomes

Watch the whole lesson, review it thoroughly, and then see if you’re ready to:

  • Recognize the session layer of the OSI model
  • List the seven layers of the OSI model
  • Discuss the responsibilities, functions and protocols of the session layer
  • Specify the six session layer protocols
x

Hi!
I'm Sigvald

Do you need a custom essay? How about ordering an essay here?

Check it out